RU2314075C1 - Surgical method for correcting presbiopia cases aggravated with complex hypermetropic astigmatism - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: method involves treating eye cornea with excimer laser radiation in multi-stage mode with optical surfaces and transition zone surface being formed by sequentially layer-by-layer removing cornea segments. Action parameters are wavelength of 193-222 nm pulse power of 0.8-2.1 mJ, laser spot diameter of 0.5-1.5 mm, pulse duration of 5-8 ns, frequency of 30-500 Hz. The first optical surface is ellipsoidal convex one arranged within the whole optical zone. When forming it, central elliptical zone that is not to be withdrawn, is traced. Central elliptical zone symmetry center is made coincide with the optical zone center, major axis of the central elliptical zone is aligned with the strong astigmatism axis and the minor axis of the central elliptical zone with the weak astigmatism axis. The second optical surface is formed as spherical concave surface which optical axis coincides with the optical zone center. The second optical surface diameter is 0.28-0.55 times as large as the optical zone diameter. Then, transition zone surfaces are formed. The first transition zone surface is formed as a part of convex external surface of annular toroid being 0.04-0.2 times as wide as action zone diameter. Its external edge is coupled with cornea portion that is not to be withdrawn. The second transition zone surface is formed as a part of concave internal surface of the second annular toroid being 0.04-0.2 times as wide as action zone diameter. The second internal transition zone surface edge is coupled with external edge of the first optical surface and its external edge is coupled with the first internal transition zone surface edge.

EFFECT: improved visual function in long and short distance; reduced luminous halation; minimized volume of withdrawn eye tissues.

24 dwg

Description

The invention relates to ophthalmology and can be used in the correction of presbyopia in combination with complex hyperopic astigmatism. The problem of presbyopia correction in combination with complex hyperopic astigmatism is one of the urgent in ophthalmology. Presbyopia is understood as a visual impairment due to the attainment of old age, it is a consequence of the loss of the elastic properties of the lens, which causes a decrease in accommodation and visual impairment near. Complex hyperopic astigmatism is a combination of spherical hyperopia with simple hyperopic astigmatism. About 8% of all presbyopes suffer from presbyopia in combination with complex hyperopic astigmatism. All this makes the problem of presbyopia correction in combination with complex hyperopic astigmatism one of the urgent problems of ophthalmology.

The well-known "Method of surgical correction of presbyopia with refractive errors" according to patent RU No. 2197209, A61F 9/01 priority of 06/06/2000

A method for surgical correction of presbyopia with refractive errors, including exposure to an excimer laser first on the cornea of the leading eye until emmetropic refraction is achieved, and then on the cornea of the paired eye until mild myopia is achieved. Additionally, the relative accommodation margin, the positive part of the focal zone of the paired eye, the optimal distance required by the patient for professional work near, and the degree of planned anisometropia to create weak myopia in the paired eye are additionally determined by the formula

D = 1 / h-0.5 · [POS (A-Fpos) + POS ((Y-35) / 10 + 0.6))],

where h is the optimal distance required by the patient for professional activities near.

However, this method has significant disadvantages: it is not possible to achieve high visual functions while minimizing the amount of tissue removed by the eye, the presence of a significant light halo.

The technical result achieved by the invention is the development of a method for surgical correction of presbyopia in combination with complex hyperopic astigmatism in order to provide high visual functions in the distance and near while minimizing the volume of removed eye tissue and reducing the light halo.

The specified technical result is solved by the fact that in the method of surgical correction of presbyopia in combination with complex hyperopic astigmatism, including the effect of radiation of an excimer laser on the cornea of the eye, optical surfaces and surfaces of the transition zone (PZ) are formed by sequential layer-by-layer removal of cornea sections; initially form the first ellipsoidal convex optical surface lying within the entire optical zone (OZ) by forming a circular impact zone to be removed, and mark the central elliptical zone (CEZ), which cannot be removed, while the center of symmetry of the CEZ is combined with the center of the optical zone , the major axis of the CEZ is combined with the strong axis of astigmatism, and the minor axis of the CEZ is combined with the weak axis of astigmatism, with each subsequent layered exposure, the area of the CEZ not to be removed is increased by the formation of a curvilinear closed figure, bounded by a circle with the radius of the impact zone and a curved line that is the outer part of the CEZ, then increase the area of the CEZ until the major axis of the CEZ are equal to the diameter of the impact zone (SV), then they continue to form an optical surface by forming two symmetric curvilinear closed figures to be removed, each of which is limited by an arc of a circle with the radius of the impact zone and a curved line that is the outer section of the CEZ; then a second optical surface is formed, the optical axis of which coincides with the center of the optical zone, the ratio of the diameter of the second optical surface to the diameter of the SC lies in the range from 0.28 to 0.55 of the diameter of the SC, in the form of a concave spherical surface, by forming concentric rings that cannot be removed with the center in the center of the optical zone containing the Central circular zone to be removed, and increase the area of the Central zone with each removed layer; then form the first surface of the transition zone (PPZ), within the area of the impact zone (SV), lying in the range from 0.04 to 0.2 of the diameter of the SV connected by the outer edge of the first PPZ with the cornea section not to be affected, in the form of a part of the convex outer surface (CVP) ) of the first annular toroid formed by the rotation of the first flat segment of a circle turned by the arc of the segment toward the optical axis, around the optical axis without intersecting this axis, while the circular arc of this segment rests on the chord located under angle to the optical axis and lying with the optical axis in the same plane, the first SCR is formed by circles to be removed, centered in the center of the optical zone, the outer diameter of which decreases in layers; then a second SCF is formed, within the area of the SC, lying in the range from 0.04 to 0.2 of the diameter of the SC connected by the inner edge of the second SCF with the outer edge of the first optical surface, and the outer edge of the second SCF with the inner edge of the first SCF, as a part of the concave inner surface ( FWM) of the second annular toroid, by rotating the second flat segment of the circle, facing the segment arc in the direction opposite to the optical axis, around the optical axis, without intersecting this axis, while the circular arc of this segment rests a chord located at an angle to the optical axis equal to the angle of inclination of the CVNP chord and lying on the same plane with the optical axis, this surface being formed by circles to be removed, centered in the center of the optical zone, the outer diameter of which decreases in layers; moreover, the effect on the surface of the cornea is produced by the radiation of an excimer laser with a wavelength of 193-222 nanometers, with an energy per pulse of 0.8-2.1 millijoules, with a laser spot diameter of 0.5-1.5 mm, a pulse duration of 5-8 nanoseconds, and a pulse repetition rate of 30 to 500 hertz .

The set of essential distinguishing features proposed by the authors is necessary and sufficient for an unambiguous positive solution of the technical problem posed: creating a method for surgical correction of presbyopia in combination with complex hyperopic astigmatism in order to ensure high visual functions in the distance and near without additional spectacle correction while minimizing the volume of removed eye tissues and light halo reduction.

The invention is illustrated by drawings. They show:

Figure 1 is a frontal section of a radiation exposure zone.

Figure 2 is a frontal section of the location of the optical and transition zones.

Figure 3 is a top view of the impact zone.

Figure 4 - alignment of the axes of astigmatism.

Figure 5 - increase in the area of the elliptical zone 14.

6 - equality of the major axis of the elliptical zone to the diameter of the impact zone.

7 is a decrease in the area of curved shapes 20.

Fig - the structure of the second optical surface 6.

Fig.9 - the formation of the second optical surface.

Figure 10 - an increase in the area of the Central zone 22.

11 - the formation of the first surface 8 of the transition zone.

12 is a plan view of a surface 8.

Fig is an isometric view of the surface 8.

Fig - frontal section of the surface 8.

Fig - the formation of a circular zone 30.

Fig - reduction of the circular zone 28

Fig - a further decrease in the circular zone 28.

Fig - formation of the second surface 9 of the transition zone.

Fig. 19 is an isometric view of a surface 9.

Fig - frontal section of the surface 9.

Fig - the formation of a circular zone 35.

Fig - reduction of the circular zone.

Fig - reduction of the circular zone.

Fig is an isometric view of the mating surfaces 8 and 9.

The method proposed by the authors is as follows.

The method consists in exposing an excimer laser 1 to the cornea of the eye 2 by sequential layer-by-layer removal of sections 3 (FIG. 1) of the cornea 2. On the cornea 2, sections 4 that cannot be removed are formed (FIG. 2).

Figure 2 presents:

the first optical surface 5;

second optical surface 6;

optical zone 7;

the first surface 8 of the transition zone;

the second surface 9 of the transition zone;

transition zone 10.

Figure 2 dots show the boundaries of the surfaces 5, 6, 8, 9, 4.

By a part of the surface of the cornea 2 to be removed is meant a portion of the cornea of a certain shape that is exposed to laser radiation 1 and removed as a result of this effect.

By a part of the surface of the cornea that cannot be removed is meant a portion of the cornea of a certain shape that is not exposed to laser radiation and cannot be removed.

By optical surface is meant the interface between two media with different refractive indices, which serves to change the path of the rays when creating a high-quality optical image on the retina of the eye.

By a layer of the cornea is meant a portion of the cornea, the shape of which changes upon a single exposure to a spatially ordered series of laser radiation pulses.

A top view of the exposure zone is shown in FIG. 3.

Surfaces 5, 6, 8, 9 are shown in FIGS. 2, 3.

By the optical zone 7 is meant the zone in which the optical surfaces 5, 6 are formed (FIG. 3).

The impact zone 11 refers to the zone in which the optical surfaces and the surfaces of the transition zone are formed.

The optical axis 12 is the axis of symmetry of all formed optical surfaces and the surfaces of the transition zones (Fig.2, 3).

The optical surfaces 5, 6 and the surfaces of the transition zone 8, 9 are formed by sequential layer-by-layer removal of corneal regions. There are also sections 4 of the cornea 2, not to be removed, located on the periphery of the cornea.

The implementation of the method should be divided into several stages.

Initially, the first ellipsoidal convex optical surface 5 is formed, lying within the entire optical zone 7, by forming the zone 13 to be removed.

Mark the central elliptical zone 14 (CEZ), not subject to removal (Figure 4). 4-7, region 14 is not shaded, and zone 13 is shaded.

The center of symmetry of the CEZ is combined with the center 12 of the optical zone 7, the major axis 15 of the CEZ is combined with the strong axis of astigmatism 16, and the minor axis 17 of the CEZ is combined with the weak axis of astigmatism 18 (Figure 4).

Zone 14 during laser irradiation is not removed during the formation of the first corneal layer that changes in shape and each of the subsequent cornea that changes in shape to create a surface 5.

Figure 4 shows, for convenience of presentation, the case where the strong axis 16 of astigmatism is vertical and the weak axis 18 is horizontal. In practice, cases with a different arrangement of the axes of astigmatism (not shown) are possible.

With each of the subsequent laser actions, the area of the CEZ 14 increases, and the area 13 decreases. At that, zone 13 is formed by a curved closed figure limited by a circle with the radius of the impact zone 11 and a curved line 19, which is the outer part of the CEZ (Figure 5). With each subsequent layered effect, the area of the CEZ 14, which cannot be removed, is increased and the area of the closed curved is reduced figures 13 (Figure 5).

The area of the CEZ, not subject to removal, is increased until the equality of the major axis 15 of the CEZ with the diameter of the impact zone 11 (Fig.6). In this case, the curvilinear zone to be removed forms two symmetric curvilinear closed figures 20, each of which is bounded by an arc of a circle 11 with the radius of the zone of influence and a curved line 19, which is the outer part of the CEZ 14. In FIG. 6, two symmetric closed figures 20 are shaded.

The formation of the optical surface is continued by the formation of the CEZ 14, which cannot be removed, and two symmetrical curved closed figures 20, which must be removed. With each subsequent layer, the area of the CEZ 14, not to be removed, is increased, and the area of the curved closed figures 20 to be removed is reduced (Fig.6, 7). Each of the curved closed figures 20 is bounded by an arc of a circle 11 with the radius of the zone of influence and a curved line 19, which is the outer section of the CEZ 14 (Fig.7). Surface 5 allows you to get high visual functions with near vision.

Then form the second optical surface 6, the optical axis of which coincides with the center of the optical zone, the ratio of the diameter of the second optical surface to the diameter of the SC lies in the range from 0.28 to 0.55 of the diameter of the SC, in the form of a concave spherical surface (Fig. 8). The surface 6 includes the center 12 of the optical zone 7.

The surface 6 is obtained by forming concentric rings 21 centered in the center of the optical zone, bounded by a circle with the radius of the impact zone 11, containing a circular central zone 22 to be removed (Fig. 9). In FIG. 9, zone 22 is hatched, and concentric ring 21 is not hatched.

Zone 22 during laser irradiation is removed during the formation of the first corneal layer of varying shape and each of the subsequent corneal layers of shape required to create the surface 6.

With each removed layer, an increase in the area of the central zone 22 and a reduction in the area of zone 21 are performed (Figure 10).

The spatial combination of all circular layers of the cornea that cannot be removed, in which the diameter of the subsequent layer of the cornea is larger than the diameter of the previous one, creates a convex spherical optical surface. Surface 6 allows you to get high visual functions with distance vision.

Then form the surface 8, 9 of the transition zone, which are the surfaces of the annular toroids. An annular toroid means a surface formed by the rotation of a circle around an optical axis without intersecting this axis. In the present invention, surfaces 8, 9 are parts of a circular toroid and are formed by rotating segments of a circle around an optical axis without intersecting this axis.

The first surface 8 of the transition zone is formed as part of the convex outer (CVP) surface of the first annular toroid (Figure 11). The surface 8 is formed by rotating the first flat segment 23, convex towards the optical axis, around the axis 12 of surface 8 without intersecting axis 12. The arc of circle 24 of segment 23 is based on the chord 25 located at an angle 26 to axis 12 and lying with axis 12 in one plane (Fig.11). Top view of the surface 8 in Fig.12. The surface 8 in isometric projection is shown in Fig.13.

The surface 8 is formed by forming circular zones 27 to be removed, bounded by a circle with a radius of the impact zone 11, with a center 12, in the range from 0.04 to 0.2 of the diameter of the impact zone.

A frontal section of the surface 8, explaining the formation of the circular zones 27, is shown in FIG. 14. Subsequently, in each layer, the area of the circular zone 27 to be removed is reduced. Positions 28, 29 show a decrease in circular zones 27. Figures 15, 16, 17 show a layer-by-layer decrease in the area of circular zones 27, 28, 29 (shaded in the figures).

The surface of the transition zone 8 is mated with a portion of the cornea 4, not subject to laser exposure.

Then form the second surface 9 of the transition zone in the form of a portion of the concave inner surface (CVP) of the second annular toroid. The surface 9 is formed by rotation of the second flat segment 30, surrounded by the opposite side from the optical axis, around the optical axis 12 without intersecting this axis (Fig. 18). The arc of a circle 31 of segment 30 is supported by a chord 32 located at an angle of 26 to the optical axis 12 of the CVT of the second toroid (Fig. 18). The surface 9 in isometric projection is shown in Fig.19.

The surface 9 is formed by forming circular zones 33 to be removed in the range from 0.04 to 0.2 of the diameter of the impact zone.

A frontal section of the surface 9 explaining the formation of the circular zones 33 is shown in FIG. 20. Subsequently, in each layer, the area of the circular zone 33 to be removed is reduced. Positions 34, 35 show the reduction of circular zones 33 (Fig.21-23). Layer by layer reduction in the area of circular zones 33-35 in FIG. 21-23 are shown in shaded areas.

The second surface of the transition zone 8 is mated with the first surface 9 of the transition zone. An isometric view of this interface is shown in FIG.

It should be noted that the inner edge of the PVI is combined with the outer edge of the PVI, and the inner edge of the PVI is combined with the outer edge of the optical surface 5.

The excimer laser effect on the cornea, according to the invention, is carried out with the following parameters: the radiation wavelength of the excimer laser is 193-222 nanometers, with a pulse energy of 0.8-2.1 millijoules, with a laser spot diameter of 0.5-1.5 mm, with a pulse duration of 5-8 nanoseconds, frequency pulse repetition from 30 to 500 hertz.

The proposed method is characterized by the following clinical examples.

Example 1: Patient B. 54 years.

Condition before surgery:

Visual acuity in the distance: Vis OD = 0.2 sph + 1.0 D cyl + 2.25 D ax 90 ° = 0.9.

Near visual acuity: Vis OD = 0.1 sph + 3.0 D cyl + 2.25 D ax 95 ° = 0.9.

Corneal curvature: 42.00 D - 90 °, 40.00 D - 0 °, average - 41.00 D.

Corneal thickness: 555 microns.

Diagnosis: Complex hyperopic astigmatism of a high degree, presbyopia.

The operation LASIK in accordance with the proposed invention.

Condition after surgery:

Visual acuity in the distance: Vis OD = 0.7 sph - 0.5 D cyl + 1.0 D ax 90 ° = 0.9.

Near visual acuity: Vis OD = 0.9.

Corneal curvature: 44.5 D - 90 °, 43.5 D - 0 °, average - 44.00 D.

Example 2: Patient A., 62 years old.

Condition before surgery:

Visual acuity into the distance: Vis OS = 0.5 sph + 2.0 D cyl +1.5 D ax 107 ° = 0.8.

Near visual acuity: Vis OS = 0.1 sph + 5.0 D cyl + 1.5 D ax 107 ° = 0.8.

Corneal curvature: 43.0 D - 107 °, 41.50 D - 17 °, average - 42.25 D.

Corneal thickness: 548 microns.

Diagnosis: Complicated mild hyperopic astigmatism, presbyopia.

The operation LASIK in accordance with the proposed invention.

Condition after surgery:

Visual acuity in the distance: Vis OS = 0.8. Near visual acuity: Vis OS = 0.7.

Corneal curvature: 45.5 D - 90 °, 46.0 D - 0 °, average - 45.75 D.

Example 3: Patient M. 53 years.

Condition before surgery:

Visual acuity in the distance: Vis OS = 0.5 sph + 3.0 D cyl + 2.0 D ax 90 ° = 0.7.

Near visual acuity: Vis OS = 0.2 sph + 4.5 D cyl + 2.0 D ax 90 ° = 0.7.

Corneal curvature: 41.0 D - 90 °, 39.0 D - 0 °, average - 40.0 D.

Corneal thickness: 548 microns.

Diagnosis: Moderate hypermetropic astigmatism, presbyopia.

The operation LASIK in accordance with the proposed invention.

Condition after surgery:

Visual acuity in the distance: Vis OS = 0.7.

Near visual acuity: Vis OS = 0.6 cyl + 0.75 D ax 90 ° = 0.7.

Corneal curvature: 44.5 D - 90 °, 44.5 D - 0 °, average - 44.5 D.

The presence of surfaces 5, 6 provides high visual functions with near and far vision.

Due to the fact that the edges of surface 5 lie below surface 4, it is necessary to form a smooth transition between the optical surface 5 and the area of the cornea 4. This role is played by the surfaces 8, 9 of the transition zone 10, made in accordance with the claims. The implementation of these surfaces in this form allows you to form a smooth transition between surfaces 5 and 4 and prevent the occurrence of the effect of a circular halo.

Minimization of the volume of removed tissue of the eye is achieved by the whole set of technological methods for implementing a spatial effect on the cornea of the eye by simultaneously combining the methods of removing and not removing curved shapes in each layer of the cornea with each exposure and the logically necessary combination of these techniques in each subsequent layer to create each of the optical surfaces 5, 6, the surfaces of the transition zone 8, 9 and maintaining the integrity of the surface 4 on the periphery of the cornea.

The whole set of essential distinguishing features of the invention indicated in the claims, including radiation parameters, provide an unambiguous positive solution to the claimed technical problem.

The use of the invention in the Federal State Institution IRTC “Eye Microsurgery” named after Acad. S.N. Fedorova made it possible to confirm an unambiguous positive solution to the stated technical problem, the development of a method for surgical correction of presbyopia in combination with complex hyperopic astigmatism to ensure high visual functions in the distance and near without additional spectacle correction while minimizing the volume of removed eye tissue.

Claims (1)

A method of surgical correction of presbyopia in combination with complex hyperopic astigmatism, including the action of excimer laser radiation on the cornea of the eye, characterized in that the optical surfaces and surfaces of the transition zone are formed by sequential layer-by-layer removal of corneal portions, initially forming the first ellipsoidal convex optical surface lying throughout optical zone (OZ), by forming a circular zone of influence to be removed, and mark not subject removal of the central elliptical zone (CEZ), while the center of symmetry of the CEZ is combined with the center of the EP, the major axis of the CEZ is combined with the strong axis of astigmatism, and the small axis of the CEZ is combined with the weak axis of astigmatism, with each subsequent layering, the area of the CEZ is increased, with the first ellipsoidal a convex optical surface is formed by forming a curvilinear closed figure to be removed, bounded by a circle with a radius of 3B and a curved line that is the outer part of the CEZ, and then increase the area The CEZ until the major axis of the CEZ are equal to the diameter of the impact zone (SV), then they continue to form the optical surface by forming two symmetrical curvilinear closed figures to be removed, each of which is bounded by an arc of a circle with a radius of the SV and a curved line that is the outer part of the CEZ, then form a second optical surface, the optical axis of which coincides with the center of the optical zone, the ratio of the diameter of the second optical surface to the diameter of the OZ lies in the range from 0.28 to 0.55 diameter OZ, in the form of a concave spherical surface, by forming concentric rings not to be removed with a center in the center of the optical zone containing the central circular zone to be removed, and increasing the area of the central zone with each layer to be removed, then the first surface of the transition zone (PPZ) is formed, lying in the range of 0.04 to 0.2 of the diameter of the pollutant conjugated by the outer edge with a portion of the cornea not to be affected, in the form of a part of the convex outer surface (CVP) of the first annular toroid formed by expanding the arc of a circle facing the optical axis around the optical axis without intersecting, the arc is supported by a chord located at an angle to the optical axis and lying with the optical axis in the same plane, with the first PPP being formed by circular zones to be removed with the center in the center of the OZ, the outer diameter of which decreases in layers, then form a second PPZ lying in the range from 0.04 to 0.2 of the diameter of the pollutant conjugated by the inner edge with the outer edge of the first optical surface, and the outer edge with the inner m edge of the first PPZ, in the form of a part of the concave inner surface (CVP) of the second annular toroid, formed by the rotation of an arc of a circle facing the opposite direction from the optical axis around the optical axis without its intersection, while the arc rests on a chord located at an angle to optical axis equal to the angle of inclination of the chord of the CVNP and lying with the optical axis in the same plane, this surface being formed by circular zones to be removed with a center in the center 03, the outer diameter of which decreases in layers, The effect on the corneal surface is produced by the radiation of an excimer laser with a wavelength of 193-222 nm, with a pulse energy of 0.8-2.1 mJ, with a laser spot diameter of 0.5-1.5 mm, and pulse durations of 5-8 ns, pulse repetition rate from 30 to 500 Hz.

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